122635ec9SAlexey Dobriyanconfig SQUASHFS 222635ec9SAlexey Dobriyan tristate "SquashFS 4.0 - Squashed file system support" 322635ec9SAlexey Dobriyan depends on BLOCK 422635ec9SAlexey Dobriyan select ZLIB_INFLATE 522635ec9SAlexey Dobriyan help 622635ec9SAlexey Dobriyan Saying Y here includes support for SquashFS 4.0 (a Compressed 722635ec9SAlexey Dobriyan Read-Only File System). Squashfs is a highly compressed read-only 84b676d2dSPhillip Lougher filesystem for Linux. It uses zlib/lzo compression to compress both 922635ec9SAlexey Dobriyan files, inodes and directories. Inodes in the system are very small 1022635ec9SAlexey Dobriyan and all blocks are packed to minimise data overhead. Block sizes 1122635ec9SAlexey Dobriyan greater than 4K are supported up to a maximum of 1 Mbytes (default 1222635ec9SAlexey Dobriyan block size 128K). SquashFS 4.0 supports 64 bit filesystems and files 1322635ec9SAlexey Dobriyan (larger than 4GB), full uid/gid information, hard links and 1422635ec9SAlexey Dobriyan timestamps. 1522635ec9SAlexey Dobriyan 1622635ec9SAlexey Dobriyan Squashfs is intended for general read-only filesystem use, for 1722635ec9SAlexey Dobriyan archival use (i.e. in cases where a .tar.gz file may be used), and in 1822635ec9SAlexey Dobriyan embedded systems where low overhead is needed. Further information 1922635ec9SAlexey Dobriyan and tools are available from http://squashfs.sourceforge.net. 2022635ec9SAlexey Dobriyan 2122635ec9SAlexey Dobriyan If you want to compile this as a module ( = code which can be 2222635ec9SAlexey Dobriyan inserted in and removed from the running kernel whenever you want), 2322635ec9SAlexey Dobriyan say M here and read <file:Documentation/modules.txt>. The module 2422635ec9SAlexey Dobriyan will be called squashfs. Note that the root file system (the one 2522635ec9SAlexey Dobriyan containing the directory /) cannot be compiled as a module. 2622635ec9SAlexey Dobriyan 2722635ec9SAlexey Dobriyan If unsure, say N. 2822635ec9SAlexey Dobriyan 29637d5c9aSPhillip Lougherconfig SQUASHFS_XATTR 3001e5b4e4SPhillip Lougher bool "Squashfs XATTR support" 3101e5b4e4SPhillip Lougher depends on SQUASHFS 3201e5b4e4SPhillip Lougher default n 3301e5b4e4SPhillip Lougher help 3401e5b4e4SPhillip Lougher Saying Y here includes support for extended attributes (xattrs). 3501e5b4e4SPhillip Lougher Xattrs are name:value pairs associated with inodes by 3601e5b4e4SPhillip Lougher the kernel or by users (see the attr(5) manual page). 3701e5b4e4SPhillip Lougher 3801e5b4e4SPhillip Lougher If unsure, say N. 3901e5b4e4SPhillip Lougher 4079cb8cedSChan Jeongconfig SQUASHFS_LZO 4179cb8cedSChan Jeong bool "Include support for LZO compressed file systems" 4279cb8cedSChan Jeong depends on SQUASHFS 434b676d2dSPhillip Lougher default n 4479cb8cedSChan Jeong select LZO_DECOMPRESS 454b676d2dSPhillip Lougher help 464b676d2dSPhillip Lougher Saying Y here includes support for reading Squashfs file systems 474b676d2dSPhillip Lougher compressed with LZO compresssion. LZO compression is mainly 484b676d2dSPhillip Lougher aimed at embedded systems with slower CPUs where the overheads 494b676d2dSPhillip Lougher of zlib are too high. 504b676d2dSPhillip Lougher 514b676d2dSPhillip Lougher LZO is not the standard compression used in Squashfs and so most 524b676d2dSPhillip Lougher file systems will be readable without selecting this option. 534b676d2dSPhillip Lougher 544b676d2dSPhillip Lougher If unsure, say N. 5579cb8cedSChan Jeong 56*7a43ae52SPhillip Lougherconfig SQUASHFS_XZ 57*7a43ae52SPhillip Lougher bool "Include support for XZ compressed file systems" 58*7a43ae52SPhillip Lougher depends on SQUASHFS 59*7a43ae52SPhillip Lougher select XZ_DEC 60*7a43ae52SPhillip Lougher help 61*7a43ae52SPhillip Lougher Saying Y here includes support for reading Squashfs file systems 62*7a43ae52SPhillip Lougher compressed with XZ compresssion. XZ gives better compression than 63*7a43ae52SPhillip Lougher the default zlib compression, at the expense of greater CPU and 64*7a43ae52SPhillip Lougher memory overhead. 65*7a43ae52SPhillip Lougher 66*7a43ae52SPhillip Lougher XZ is not the standard compression used in Squashfs and so most 67*7a43ae52SPhillip Lougher file systems will be readable without selecting this option. 68*7a43ae52SPhillip Lougher 69*7a43ae52SPhillip Lougher If unsure, say N. 70*7a43ae52SPhillip Lougher 7122635ec9SAlexey Dobriyanconfig SQUASHFS_EMBEDDED 7222635ec9SAlexey Dobriyan bool "Additional option for memory-constrained systems" 7322635ec9SAlexey Dobriyan depends on SQUASHFS 7422635ec9SAlexey Dobriyan default n 7522635ec9SAlexey Dobriyan help 7622635ec9SAlexey Dobriyan Saying Y here allows you to specify cache size. 7722635ec9SAlexey Dobriyan 7822635ec9SAlexey Dobriyan If unsure, say N. 7922635ec9SAlexey Dobriyan 8022635ec9SAlexey Dobriyanconfig SQUASHFS_FRAGMENT_CACHE_SIZE 8122635ec9SAlexey Dobriyan int "Number of fragments cached" if SQUASHFS_EMBEDDED 8222635ec9SAlexey Dobriyan depends on SQUASHFS 8322635ec9SAlexey Dobriyan default "3" 8422635ec9SAlexey Dobriyan help 8522635ec9SAlexey Dobriyan By default SquashFS caches the last 3 fragments read from 8622635ec9SAlexey Dobriyan the filesystem. Increasing this amount may mean SquashFS 8722635ec9SAlexey Dobriyan has to re-read fragments less often from disk, at the expense 8822635ec9SAlexey Dobriyan of extra system memory. Decreasing this amount will mean 8922635ec9SAlexey Dobriyan SquashFS uses less memory at the expense of extra reads from disk. 9022635ec9SAlexey Dobriyan 9122635ec9SAlexey Dobriyan Note there must be at least one cached fragment. Anything 9222635ec9SAlexey Dobriyan much more than three will probably not make much difference. 93